Method and device for incinerating radioactive wastes and preparing burnable wastes for non-polluting storage

ABSTRACT

An apparatus for incinerating radioactive wastes includes a furnace which has air inlet conduits and a flue gas outlet conduit and air heaters as well as blowers connected to the air inlets for forcing hot air into the furnace. The apparatus further has a feeding device connected to the charging end of the furnace for introducing liquid or solid wastes thereinto and a device which communicates with the discharge end of the furnace for removing solid reaction products from the furnace. In the flue gas conduit there is connected a plurality of flue gas filters each containing filter candles, a flue gas chamber and a mechanism for removing ashes from the flue gas chamber. The apparatus also includes a mixer section connected with the outlet of each flue gas filter and having a mechanism for mixing cool air with the flue gas filtered by the flue gas filters. Gas blowers connected to the output of the mixer section draw the gas from the apparatus.

United States Patent 11 1 1111 3,922,974 Hempelmann 1 1 Dec. 2, 1975 [5METHOD AND DEVICE FOR 3.457.881 7/1969 Test ct al. 110/7 {NCINERATINGRADIOACTIVE WASTES 3,697,256 10/1972 Englc 110/8 X AND PREPARINGBURNABLE WASTES FOR NON-POLLUTING STORAGE Primary ExaminerKenneth W.Sprague Attorney, Agent, or FirmSpencer & Kaye [57] ABSTRACT Anapparatus for incinerating radioactive wastes includes a furnace whichhas air inlet conduits and a flue gas outlet conduit and air heaters aswell as blowers connected to the air inlets for forcing hot air into thefurnace. The apparatus further has a feeding device connected to thecharging end of the furnace for introducing liquid or solid wastesthereinto and a device which communicates with the discharge end of thefurnace for removing solid reaction products from the furnace. In theflue gas conduit there is connected a plurality of flue gas filters eachcontaining filter can dles, a flue gas chamber and a mechanism forremoving ashes from the flue gas chamber. The apparatus also includes amixer section connected with the outlet of each flue gas filter andhaving a mechanism for mixing cool air with the flue gas filtered by theflue gas filters. Gas blowers connected to the output of the mixersection draw the gas from the apparatus.

18 Claims, 8 Drawing Figures US. Patent Dec. 2, 1975 Sheet 1 of 83,922,974

Sheet 2 of 8 US. atsnt Dec. 2, 1975 US. atant Dec. 2, 1975 Sheet 3 of 83,22,9'74

Dec. 2, 1975 Sheet 4 of 8 3,922,974

US. Patent Dec. 2, 1975 Sheet 5 of8 3,922,974

US. Patent Dec. 2, 1975 Sheet 6 of8 3,922,974

US. Patent Dec. 2, 1975 Sheet 7 of8 3,922,974

Sheet 8 of 8 3,922,974

U.S. Patent Dec. 2, 1975 The present invention relates to a method and adevice for incinerating radioactive wastes and preparing burnableradioactive wastes for non-polluting storage.

Methods and devices for incinerating radioactive burnable wastes havebeen described in the literature repeatedly. Incineration serves thepurpose of minimizing the volumes of radioactive wastes and transformingthem into a condition which positively excludes any digestion,fermentation or even fire during storage. However, incineration causes anumber of problems, such as the very uniform, uninterrupted combustionof material whose composition changes continuously; the calorific valueof burnable wastes varying between approximately 2,800 and 10,000kcal/kg, or the positive prevention of any escape of radionuclides fromthe furnace, or the flue gases which may be very corrosive, depending onthe type of waste.

Pregrading of burnable wastes, crushing and mixing such wastes couldnarrow down the range of calorific values causing these difficulties,but the capital cost and the additional space requirements connectedwith grading devices, a crusher, a mixer, and a silo with the respectivefeeding system are negative factors associated with such plants. Becauseof the high capital cost connected with incineration devices only plantswith large throughputs (in excess of 50 kg/h) can be oper-- ated at anapproximately economical level. Correspondingly, several incinerationplants had to be closed down because of technical difficulties oruneconomical operation.

The incineration devices for radioactive wastes used so far are notbased on a uniform design principle. Both combustion furnaces with andwithout auxiliary heaters can be found. The air supply to the furnacesis directed either from the top to the bottom or vice versa. Frequently,wet scrubbers are used to clean the flue gases. Incineration of wastescontaining a high percentage of plastics generates very aggressive(corrosive) flue gases, which gives rise to condensates in the colderparts of the unit containing hydrochloric acid and tar.

An incineration device (pilot plant) for a throughput of approximately30 kg/h consisting of an electrical air heater with air supply control,an incineration furnace bricked up in several layers with a rotary steelplate acting as the grate for removal of the ashes, and a simple slidinglock for feeding the waste into the furnace, a bricked-up flue gas linewith valves, two parallel afterburning chambers (coarse filters), onefine filter with 49 ceramic filter candles installed in a cast ironplate, and a lid which can be removed if filter candles must beexchanged, a twostage water receiver acting as a tar separator, with acontrol system installed in a by-pass, and two rotary piston blowers, isdescribed by W. Hempelmann and H. Krause in the periodical Chemie-Ingenieur-Technik, Volume 42, Issues 9 10 (1970), pages 645-653.

Disadvantages of this plant are the lack of economy resulting from thelow throughput, the relatively large damage due to corrosion of metalparts occurring after relatively short periods of operation, thefrequent cleaning and repair periods following upon relatively shortoperating periods, and the watchfulness high re- 2 quirements on thealertness and qualification of the operating crew.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method of incinerating radioactive wastes and preparingburnable radioactive wastes for non-polluting storage, which operateswith a maximum of economy, i.e. which can be used to process anyburnable waste generated in the solid or liquid state, practicallywithout any preliminary treatment and without any grading, reducing itto the minimum possible volume in a safe and simple way and transformingit into a condition which is no longer burnable and thus fit forpermanent storage. Another object of the present invention is to providea device for the implementation of this method which can be operatedwith a minimum of energy, gives rise to practically no corrosionproblems, can be operated also during replacement of filter candles, isrelatively easy to repair and allows easy replacement of parts subjectto wear and which further ensures a maximum of safety to the operatingcrew with respect to fire hazard and ionizing radiation duringoperation, and also during the replacement of filter candles and partssubject to wear as well as during the removal of ashes and solidincineration products and with respect to the discharge of flue gases,despite the accumulation of radionuclides in the furnace and in thefilters as the period of operation increases. Moreover, the presentdevice and parts thereof, respectively, will have prolonged servicelives, i.e., the period of operation up to cleaning or replacement ofparts subject to wear will be extended. On the one hand, the presentdevice can be operated by personnel trained on the job, and, on theother hand, it will require only a minimum of personnel. It will becompact, requiring a minimum in terms of capital costs.

In the present invention this problem is solved in that wastes with lowand high calorific values are combined and fed into an incinerationfurnace in such a way that the enery required for incineration, exceptthe fraction needed for pre-heating in the start-up phase, is taken fromthe wastes proper, both solid and liquid wastes are fed into the furnaceand burnt, the different increases in temperature of the flue gasesgenerated during incineration as a consequence of different calorificvalues of the materials incinerated are limited by cooling only, and thesolid reaction products are removed in containers so that they can besolidified and made into blocks fit for storage. In a furtherdevelopment of the present invention, the flue gases generated in theprocess of incineration are burnt completely and cleaned in a secondcombustion stage requiring only the energy contained in these fluegases, the temperature in the zone of the incineration reactions is keptin a range of approximately 1000C to approximately 1200C at a vacuumbetween and mm of water, and the temperature in the afterburning zone isin the range between approximately 800 and 900C, whereas the temperaturein the fine cleaning zone ranges between approximately 550C andapproximately 650C.

A preferred embodiment of the device according to the present inventionfor the purpose of implementing the method is characterized by atripartite fumace without a grate, with several air supply systems and aflue gas discharge system, a feeding device, a device for feedingliquids, and a device for'the removal of solid reaction products, byseveral flue gas filters, which can be operated alternately, connectedwith the flue gas discharge of the furnace by way of a flue gas lineequipped with an explosion damper and containing devices for thereplacement of filter candles, flue gas surge chambers and devices forthe removal of ashes, and by several pure gas blowers connected paralleldownstream of a mixer section for cooling air, and several air heatersconnected upstream of the furnace and supplied with air by a forceddraft blower.

In a further developement of the present invention the furnace consistsof a cylindrical frame divided into three sections each of which isequipped with flanges, the top section together with the center sectionis arranged in a top chamber, the bottom section is arranged in a bottomchamber separate from the top chamber, the center chamber stands onbrackets on a platform separating the top from the bottom chamber, itsbottom section penetrating into the bottom chamber, the top and bottomsections are removable parts subject to wear, the top section isdesigned as a lid with a feed aperture connected with the feedingdevice. It further includes. a device for feeding liquids, and an aircooled sight glass; the center section is equipped with two air inletsystems and a flue gas discharge system, the bottom section is connectedwith a device for the removal of solid reaction products by means of anaperture which can be locked and has a movable damper to close theaperture during incineration and release the entire cross section of theaperture while the solid reaction products are removed; in addition,there is an air inlet system directed at the damper; on the inside ofthe three sections of the frame the furnace contains a refractoryceramic lining consisting of several layers and closed on the inside, atleast the outer layers of which lining in the center section rest onangular brackets of heat resistant steel attached to this centersection. In a preferred embodiment, the air inlet systems in the bottompart of the center section and in the bottom section are arrangedtangentially relative to the interior and in opposed directions relativeto each other, whereas the air inlet system used for cooling purposes isarranged radially in the center section below the flue gas discharge.The interior of the center section is cylindrical, the interior of thebottom section initially tapers conically down to one third of thediameter, which part is followed by a uniformly cylindrical section.

In another embodiment of the device according to the present inventionthe feeding system is a double lock connected with the lid of thefurnace so as to be removable and consists of a steel vessel whoseinside is lined with an insulating material and which contains a slidedamper movable in its interior, a bottom discharge which can be closedby the slide damper and is opened only while the furnace is loaded withsolid wastes, a waste feed aperture which can be closed with a lid, anda maintenance aperture arranged over the bottom discharge and to beclosed with a lid. The slide damper closing or uncovering the bottomdischarge consists of a ceramic plate with an aperture of the samediameter as that of the bottom discharge, a pot installed above theaperture and expanding slightly concically towards the bottom with anangle plate connecting plate and pot, with a push rod connected to thisangle plate and a compressed air cylinder. A steel plate is fitted witha small amount of clearance between the plate and the pot and rigidlyconnected to the wall of the feeding device to prevent wastes fromsticking to the bottom of the feeding device. In a preferred embodimentof the present invention the device for removing solid reaction productsconsists of a glove box and an intermediate lock, through which thedevice for the removal of solid reaction products is connected to thefurnace so as to be removable; the intermediate lock can be separatedfrom the glove box, and it consists of a container with several socketswhich can be closed by lids; the movable damper for closing the furnaceis located in the container, one side of the container is so designed asto completely accommodate the opened damper while the solid reactionproducts are removed; the glove box contains several glove openings theinside of which can be closed by plugs; two windows are arrangedopposite each other and there is a damper consisting of two parts,closing the glove box against the intermediate lock and movable downwardin front of the windows to protect the windows during the removal of thesolid reaction products; the bottom opening of the glove box is equippedwith a coarse grating. The glove box for removal of the solid reactionproducts is equipped with a flushing connection, a lock for tools, and alarge-area explosion damper.

In another embodiment of the present device, the flue gas filtersconsist of cylindrical steel frames covered with refractory ceramiclinings and conically taper towards the bottom to one of the aperturesused for the removal of ashes, they are equipped with one flue gas inleteach, one outlet each for the waste gas cleaned by afterburning andfiltering, one inlet or outlet aperture each for the preheating gasrequired prior to startup of the respective flue gas filter, and oneexplosion'damper each and each carries a plate made of steel or aceramic material covered with a multitude of ceramic filter candles andhas one bricked-up lid each; their upper ends are detachably connectedto a device for filter candle replacement, and their bottom ends aredetachably connected to adevice for the removal of ashes. In a differentembodiment of the present device, at least some of the flue gas filtershave a square shape the bottom section of which tapers downward in thedirection of an aperture for the removal of ashes. The flue gas inlet isinstalled at the upper end of the tapered part of the flue gas filterand the plate with the filter candle is installed at the upper end ofthe cylindrical or square part of the flue gas filter. The cylindricalor square interior of the flue gas filter between the flue gas inlet andthe bottom ends of the vertically suspended filter candles, which can beexchanged in the plate and are fitted so as to be gastight, is designedas a flue gas surge chamber. The device for the removal of ashes isdesigned as a glove box (box for filter ashes). The box for filter asheshas several glove ports, at least one lock for the introduction of toolsand at least one window and a swiveling damper closing and opening theaperture for the removal of ashes of the flue gas filter, respectively,and carries a coarse grating at the bottom end.

In a preferred development of the present invention, the device forreplacing filter candles is designed as a removable glove box (removablebox). The removable box consists of a housing the bottom part of whichis fitted to the flue gas filter without a lid, the top part of whichconically tapers upward and is equipped with several glove ports, atleast one lock 'for the introduction of tools, and a locking device forarresting in the bottom part of the housing, the plate pulled into theremovable box for replacing the filter candles, at least one window inthe top part of the housing and a device which serves for lifting theplate and which penetrates the housing in a gastight manner. The liftingdevice consists of a grip and a pull rod.

In another development of the present invention, the replacement devicefor filter candles is designed as a glove box (fixed box) arranged ontop of the lid and attached to the steel frame. The fixed box has aninside diameter sufficiently large to allow the lid to be moved up anddown inside the box and is equipped with several glove ports, at leastone tool lock, at least one window and a pull rod connected to the coverand penetrating the wall of the fixed box in a gastight manner, and adevice for arresting the cover pulled above the level of the window forreplacement of the filter candles.

Upstream of the inlet and outlet openings of the flue gas filters theflue gas line is equipped with flue gas valves which are angle valvesand which can be controlled manually and/or remotely. In a preferredembodiment of the present device, the flue gas line is equipped withseveral layers of a refractory lining, it contains tee-connections forcontrol and cleaning purposes. Each of the angle valves consists of aT-shaped valve housing made of steel plate and covered with severallayers of a refractory lining, a valve body spherically turned fromround steel and attached to a valve rod so as to be movable, and a ringmade of heat resistant steel as the valve seat arranged above the liningon the inlet side of the valve. The device used for feeding liquidsconsists of a double tube, an inner tube for feeding burnable liquidsinto the furnace and an outer tube for compressed-air feeding in orderto atomize the liquid and cool the inner tube.

The method and the device, respectively, according to the presentinvention can be used to burn or incinerate wastes consisting mainly of,for instance, paper, wood, filter material, rubber gloves, overshoes,clothes, animal carcasses, ion exchange resins, organic solvents orplastics. Because practically all of the device is lined with ceramics,there will be no corrosion problems. All the incineration devicespreviously known either had major problems of corrosion or could not beused to burn specific types of waste, such as polyvinyl chloride (PVC).All these plants require additional burners, which increase the amountof flue gas produced and, hence, the required filter area. Thesedisadvantages are avoided in the method and the device according to thepresent invention. The present device can be built to any sizetechnically and economically required and desirable and can thus beadapted to any meaningful throughput of radioactive wastes.

The device contains only a small number of mechanically moved parts; itrequires no water receiver as a tar separator, etc. Since the device ispreheated prior to startup and coarse filters are used for afterburningvia a by-pass line by means of air heaters, the plant can be started upwith a minimum of wear and the flue gas filters can be operateduniformly and continuously, even if the coarse filter or the fine filtermust be replaced, for instance, when filter candles are replaced. Thefine filter is necessary to prevent radionuclides from escaping from thecoarse filter into the waste gas line, especially if there is a defectin the coarse filter which has not yet been detected. Parallelconnection of several coarse and fine filters, respectively, andpreheating of the flue gas filters make the service life of a pair offilters practically unlimited. Hence, the service life of the presentdevice is no longer a function of the service life of the flue gasfilters and the filter candles, respectively, but

6 only of the service life of the furnace and other components of thedevice.

The advantageous design of the feeding device, for instance the designas a removable double lock, or the design of the slide damper with aceramic plate and a pot conically tapering downward, and the steel platebetween the pot and the bottom of the device attached to the wall of thedevice reduce the heat dissipated from the furnace into the feedingdevice, prevent a potential, undesired release of radionuclides into thefeeding device and practically exclude the possibility that wastes stickto the bottom of the device and adhere to the pot.

The subdivision into three sections of the frame of the furnace allowsthe lid and the bottom section, both of which are subject to wear, to beremoved after separation of the closed ceramic lining. This isparticularly important for replacement and repair of the bottom sectionof the furnace because this work can be performed in a room separatefrom the other components of the furnace, which greatly reduces thecontamination hazard and radiation exposure of the personnel which mightbe due to the radioactively highly contaminated lining of the centersection.

If the flue gas filters are strongly alpha-contaminated, the fixed boxis advantageous in replacing filter candles because it allows theirreplacement without any hazard of contaminating the environment. Theremovable box, on the other hand, allows all the filter candles in anumber of flue gas filters to be replaced one after the other by meansof one box only. Moreover, removal of the lid of the flue gas filter canreduce the cooling time of the filter. Because of the greater hazard ofcontamination the removable box can be used only with B-and'y-contaminated filters.

Square flue gas filters can be set up in a space saving, compactarrangement with relatively short flue gas lines. Because of theirrectangular base, the respective devices for replacing filter candlesoffer advantages of shape with respect to the manipulations to becarried out, provided that the dimension are fixed appropriately.

The special design of the flue gas valves ensures circular sealing ofthe edges, i.e. proper seating of the body of the valve on the steelring, even if the valve body is polluted or sealed. In the case of scaleformation the valve will be adjusted automatically when closing. Whilein operation, the closed valve is in the turbulent region. With thevalve open, the body of the valve is also located in the turbulentregion and the valve rod is protected. The valves are not used tocontrol the gas flow; they are only opened or closed all the way.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is explainedbelow on the basis of one embodiment represented in the diagrams.However, FIGS. 17'constitute no limitation of the present invention.

FIG. 1 is a schematic survey diagram showing an exploded view of themain components of the device for the sake of better clarity.

FIG. 2 shows an incineration furnace 3 with its most important detailsand, not shown in detail, a feeding device 4 and a device 5 for theremoval of solid reaction products with a waste drum 6 located within aradiation shield.

FIG. 3 shows a feeding device 4, FIG. 4 a device 5 for the removal ofsolid reaction products from the furnace FIG. shows a flue gas filter 7or 8 in operation with a device for replacing filter candles (fixed box)74 into which the lid 72 of the flue gas filter 7 or 8 is drawn duringreplacement of the filter candles, and a device 75 for the removal ofashes with the waste drum 6 set up underneath.

FIG. 5a represents part of FIG. 5 during replacement of a filter candle;the lid 72 of the flue gas filter 7 or 8 has been drawn into the fixedbox 74 and arrested so that the ceramic filter candles 71 can be knockedout of their support plate 70.

FIG. 6 shows a device for replacing filter candles (removable box) 73,which can be used for all flue gas filters 7 or 8 of the same design,during replacement of a filter candle and attached to a flue gas filter(shown only as a fragment). For this purpose, the lid 72 is removedbefore the removable box 73 is attached. For removal of the spent filtercandles 71 the plate 70 is drawn into the box by means of the liftingdevice 91 and the plate 70 is arrested. Now the filter candles 71 areaccessible.

FIG. 7 shows a flue gas valve 101.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, beforestartup the device is pre-heated to approximately 400 C by means ofelectrical air heaters 2. The air heaters are of the conventional typeand are supplied room air by means of a forced draught blower 1 of knowndesign. The solid radioactive wastes, normally packed in plastic bags,are introduced into the furnace 3 by means of the feeding device 4. Thewaste drops into the furnace and is ignited in the bottom section 23(FIG. 2). The flue gas generated is removed in the upper part of thecenter section 22 through the flue gas discharge 17, and is fed throughthe lined flue gas line 9 into a flue gas filter (coarse filter) 7 whichhad been pre-heated before by means of the by-pass line 11. The flue gasflows from below through the porous ceramic filter candles 71 (FIG. 5)which are open at the top only. All the filter candles taken togetherconstitute a relatively large contact area for afterburning of unburntor incompletely burnt substances contained in the flue gas which may begenerated especially in the combustion of polyethylene and otherplastics. The pre-cleaned flue gases leave the coarse filter 7 throughthe discharge 69 and are run into a similar flue gas filter which isused as a fine filter 8. After fine filtering, the clean gas is mixedwith air at room temperature in a mixer section 12, cooled in this wayand forced by flue gas blowers 13 past a radiation monitoring device 14into a stack 15. The mixer section 12 and the flue gas blowers 13 arealso conventional designs.

Turning once more to FIG. 2, solid wastes are moved into the interior 33of the center section 22 through the feed aperture 27 in the top sectionof the furnace 21, on top of which aperture the feeding device 4 islocated. Liquid wastes are continuously injected by a metering pump intothe interior 33 through the device 16 in the lid of the furnace 21. Thedevice 16 can be removed from the fumace for protection against scalingor melting. The remaining aperture will then be closed. The incinerationprocess can be supervised through an air cooled sight glass 28 in thelid of the furnace 21. The air inlet 19 is directed at the damper 30closing the interior 34 of the bottom section 23. The air cools thisdamper and prevents it from being plugged or from sticking caused byashes or solid reaction products. It may be observed in FIG. 4 that asthe damper 30 is lowered, it frees the entire cross-section of theaperture 29, thus causing solid reaction products and ashes to fallthrough a device 5 consisting of an intermediate lock 52 and a glove box51, through a coarse grating 61 into a waste drum 6. The two air inlets18 and 19 are arranged tangentially and in opposed senses so as toachieve good mixing. The air flows are controlled by means of throttles18a and 19a installed in the air inlets. The air inlet 20 with thethrottle 20a is used only to cool the flue gases, which is achieved by aradial admission of cooling air.

Due to the subdivision of the furnace 3 into three sections 21, 22 and23, each of which is equipped with flanges, and the design of the centersection 22, which is supported on a platform 25 by brackets 24 and whosebottom section 26 penetrates into a separate chamber underneath theplatform, the top section 21 and the bottom section 23, which arecomponents subject to wear, can be removed, for instance for purposes ofrepair. At least the outer layers of the multi-layered refractoryceramic lining 31 rest upon angular brackets 32 made of heat-resistantsteel and attached to the bottom end of the frame of the center section22. After separation of the ceramic lining 31, which is closed on theinside, the bottom section 23 can be disengaged from the bottom part 26of the center section 22. After reattachment of the bottom section 23,the refractory lining 31 must be repaired and closed.

The feeding device 4 represented in FIG. 3 is connected with the feedingaperture 27 in the lid of the furnace 21 by means of its bottomdischarge opening 38. The feeding device 4 essentially consists of asteel vessel 35 lined with an insulating material 36, and a speciallydesigned slide damper 37. The slide damper consists of a ceramic feederplate 37a with an aperture 43 the dimensions of which correspond tothose of the bottom discharge 38, a bottomless pot or hood 44 which isarranged above the aperture 43, and into which the solid wastes areintroduced through the waste feed aperture 39, an angular section 45connecting the pot 44 and the ceramic plate 37a which a push rod 46attached to this angular section which is moved by means of a compressedair cylinder 47. For feeding wastes into the feeding device 4, the slidedamper 37 is pushed in. In this position the plate 37a closes the bottomdischarge 38 and a steel shielding plate 49 rigidly connected with thewall of the vessel 50 separates the operature 43 of the ceramic plate37a from the pot 44, thus avoiding that wastes stick to the bottom ofthe vessel 48. If the pot 44 is filled with waste, the aperture 39 isclosed with a lid 40, and the slide damper 37 is pulled outward untilthe opening 43 arrives in registry with the bottom discharge 38 and thewaste drop into the furnace 3. The aperture 41 closed with a lid 42 isused for cleaning of the furnace 3 and for slag removal. Since thevessel 35 is closed while the furnace is loaded, except for thedischarge 38, no radioactively contaminated flue gases can escape.

As is shown in FIG. 4, the device 5 for the removal of solid reactionproducts from the furnace 3 consists of an inermediate lock 52 flangedonto the bottom end of the furnace and a glove box 51 attached to it.For the removal of solid reaction products the damper 30 is moveddownward into the intermediate lock 52, which intermediate lock mainlyconsists of a vessel 53 with 9 several sockets 54 which can be closedwith lids 55. At the same time, the damper 59 consisting of two parts,which closes the glove box 51 at the top, is moved in front of the twowindows 58 for protection. The reaction products and the ashes drop intothe waste drum 6 through the opening 60 equipped with a coarse grating61. For crushing large pieces of slag which will not pass through thegrating 61 the glove box 51 is equipped with glove ports 56 which can beclosed with plugs 57 from the inside. Moreover, the box 51 is equippedwith a large area explosion damper 64, a flushing connection 62, and atool lock 63.

The flue gas filter 7 or 8 shown in FIG. comprises a steel frame 65 witha ceramic lining 66. The flue gases emanating from the furnace 3 or fromthe coarse filter 7 enter the filter through the flue gas inlet 68, flowthrough the surge chamber 76 and afterwards pass through the porousfilter candles 71 (closed at their bottom ends 77) from the outside tothe inside and are removed through the discharge opening 69. The ashesgenerated in afterburning at the filter candles 71 are dropped into theash removing device (box for filter ashes) 75 through the aperture 67for the removal of ashes after opening the movable closing damper 83 andare passed through a coarse grating 84 and dropped into a waste drum 6.The filter candles are suspended in a steel or ceramic plate 70 restingon the lining 66. The flue gases are withdrawn above the plate. Thepreheating gas required before startup of the filter either flows intothe filter through the flue gas inlet 68 and out through the opening 78or, for instance prior to changing over to a parallel filter, enters thefilter through the opening 78 and leaves it through the discharge 69.The filter is protected against sudden conflagration by an explosiondamper 79 of the same type as that installed in the flue gas line 9 anddesignated with the reference number 10. The box 75 for filter ashescontains several glove ports 80, at least one window 82, at least onetool lock 81 to crush on the grate 61 the fragments of spent filtercandles 71 during the replacement of filter can dles.

The device 74 for replacing filter candles is shown in FIGS. 5 and 5a.This is a fixed box, i.e., a glove box fixed to the steel frame 65 ofthe flue gas filter 7 or 8 which remains on that filter even while thelatter is in operation, i.e., it should not be used for the replacementof filter candles of several filters. It is so designed that the lid 72of the filter 7 or 8 can be pulled into the box up to or above thewindow or windows 98 by means of the pull rod 99 connected with the lid72 and penetrating gastight through the wall of the fixed box 74. Thefixed box 74 is equipped with an arresting device 100 retaining the lid72 in the lifted position. Afterwards, the filter candles 71 can bereplaced through the glove box apertures 96 and the tool lock 97,respectively.

In FIG. 6, a different design of a replacement device 73 for filtercandles is shown which is attached to the filter after removal of thelid 72 of a filter 7 or 8. This device 73, which is a removable box, isattached to several filters for replacement of the filter candles. Itconsists of an upper part 86 and a lower part 85 into which the plate 70with the filter candles 71 is drawn for the replacement of filtercandles by means of a lifting device 91 penetrating gastight through thehousing 87 of the removable box 73 and locked by means of a lockingdevice 90. The lifting device 91 consists essentially of a pull rod 95and a grip 93 engaging into hooks 94 attached to the plate 70. The upperpart 86 of the removable box 73 tapers conically towards the top and isequipped with at least one window 92. Filter candles 71 are replacedthrough the glove box apertures 88 and the tool lock(s) 89,respectively, in the lower part of the removable box 73.

FIG. 7 shows a design of a flue gas valve 101 designed as an angle valvealso equipped with a multi-layer refractory lining 103, like the fluegas line 9 which is designated with the reference number 102 in FIG. 2.The angle valve 101 comprises of a T-shaped valve housing 104 made ofsteel plate and a valve body 106 machined spherically out of round steeland pivoted to a valve rod 105. In the closed position the valve issealed by the valve body 106 which engages the annular valve seat 107made of heat resistant steel arranged inwardly of the lining 103.

What we claim is:

1. An apparatus for incinerating radioactive wastes and preparingcombustible radioactive wastes for nonpolluting storage, comprising incombination:

a. a grateless furnace being formed of vertically adjoining top, centerand bottom sections each defining an inner space, said furnace having acharging end in said top section and a discharge end in said bottomsection;

b. a movable damper means positioned in said bottom section for closingsaid discharge end during incineration;

c. a first air inlet conduit communicating with the inner space definedby said center section;

d. a second air inlet conduit merging tangentially with the inner spacedefined by said bottom section, in the zone of said discharge end; saidsecond air inlet conduit being oriented towards said damper means in adirection opposite to the orientation of said first air inlet conduit;

e. means disposed externally of said furnace for dividing the spacesurrounding said furnace into an upper external space surrounding saidtop and center sections and into a lower external space surrounding saidbottom section;

f. a flue gas outlet conduit communicating with the inner space definedby center section;

g. a removable solid waste feeding device communicating with saidcharging end and being supported by said top section;

h. a liquid waste feeding device communicating with said charging endand being supported by said top section;

i. a flue gas filter having an input connected to said flue gas outletconduit; filter candles; means for replacing the filter candles; a fluegas surge chamber; means for removing ashes from the flue gas surgechamber; and an outlet; and

j. a removable glove box attached to said discharge end of said furnace;said glove box having an inlet provided with a two-part gate forcontrolling the outflow of solid material from said furnace and anoutlet provided with a coarse grate.

2. An apparatus as defined in claim 1, wherein said flue gas filter hasa square shape tapering down towards the bottom to an aperture for theremoval of ashes.

3. An apparatus as defined in claim 1, wherein said liquid waste feedingdevice includes a double tube formed of an inner tube for feeding thebumable liquid into the furnace and an outer tube for admittingcompressed air to dissipate the liquid and cool the inner tube.

4. An apparatus as defined in claim 1, the inner space defined by saidcenter section having a cylindrical configuration, the inner spacedefined by said bottom section having an upper chamber portion ofdownwardly tapering conical shape, the diameter of a lower terminus ofsaid upper chamber portion being one third the diameter of an upperterminus of said upper chamber portion; the inner space defined by saidbottom section further having a lower chamber portion of uniformcylindrical shape, said lower chamber portion adjoining said upperchamber portion and extending downwardly therefrom.

5. An apparatus as defined in claim 1, said solid waste feeding deviceincluding a vessel having a floor; means defining an opening in saidvessel floor for communicating with said charging end of said furnace; aslide damper movably supported in said vessel and cooperating with saidopening to control the discharge of solid wastes from said vessel intosaid furnace; and means defining a further opening in said vessel forintroducing solid wastes thereinto.

6. An apparatus as defined in claim 5, said slide damper including afeeder plate movable along the vessel floor, means defining an aperturein said plate, said aperture having substantially the same dimensions assaid opening in said vessel floor; an upright, laterally closed,open-ended, upwardly slightly tapered hood disposed above said apertureand affixed to said feeder plate; an actuating rod affixed at leastindirectly to said feeder plate and projecting outwardly from saidvessel; and power cylinder means operatively connected to said actuatingrod.

7. An apparatus as defined in claim 6, further including a shieldingplate affixed to said vessel and extending parallelspaced from saidvessel floor adjacent said opening; said shielding plate extendingbetween said hood and said feeder plate above said aperture in saidfeeder plate when said feeder plate covers said opening in said vesselfloor.

8. An apparatus as defined in claim 7, wherein said feeder plate is madeof ceramic and said shielding plate is made of metal.

9. An apparatus as defined in claim 1, said glove box further having twooppositely arranged observation windows; said two-part gate beingpivotally supported and covering said observation windows when in aposition in which it frees the inlet of said glove box.

10. An apparatus as defined in claim 1, said filter candles having upperends connected to said means for replacing the filter candles; saidfilter candles having 12 lower ends detachably connected with said meansfor removing ashes from the flue gas surge chamber.

11. An apparatus as defined in claim 1, wherein said gas filter includesmeans defining a cylindrical chamber below said filter candles, saidcylindrical chamber constituting said flue gas surge chamber.

12. An apparatus as defined in claim 1, wherein said gas filter includesmeans defining a square chamber below said filter candles, said squarechamber constituting said flue gas surge chamber.

13. An apparatus as defined in claim 1, wherein said means for removingashes from the flue gas surge chamber is constituted by a glove boxattached to the outlet of said gas filter.

14. An apparatus as defined in claim 13, said glove box attached to theoutlet of said gas filter having several glove ports, at least one toollock, at least one window, a movable damper closing and clearing theoutlet of said gas filter for the removal of ashes from the flue gasfilter and a coarse grate disposed at the lower end of said glove boxattached to the outlet of said gas filter.

15. An apparatus as defined in claim 1, said means for replacing thefilter candles in the flue gas filter including a. a filter candlesupport plate from which said filter candles are suspended;

b. a removable box attached to an upper part of the gas filter;

c. lifting means supported by said box for vertically moving said filtercandle support plate;

d. at least one tool lock provided in said box; and

e. an arresting device aflixed to said box for locking said filtercandle support plate in a lifted position within said box.

16. An apparatus as define in claim 1, wherein said gas filter includesa frame and a vertically movable lid; said means for replacing thefilter candles includes a fixed glove box disposed about said lid andpermanently affixed to said frame.

17. An apparatus as defined in claim 16, wherein said fixed box has asufficient inner width to allow the lid to be moved up and down therein,several glove ports, at least one tool lock, at least one window and apush rod connected with the lid and penetrating the wall of the fixedbox in a gastight manner, an arresting device for locking the lid whenpulled up beyond the level of the window for the replacement of filtercandles.

18. An apparatus as defined in claim 1, said center section including amultilayer refractory ceramic lining; further comprising angularbrackets supported on said bottom section; at least the outer layers ofsaid lining being supported upright by said angular brackets.

1. An apparatus for incinerating radioactive wastes and preparingcombustible radioactive wastes for non-polluting storage, comprising incombination: a. a grateless furnace being formed of vertically adjoiningtop, center and bottom sections each defining an inner space, saidfurnace having a charging end in said top section and a discharge end insaid bottom section; b. a movable damper means positioned in said bottomsection for closing said discharge end during incineration; c. a firstair inlet conduit communicating with the inner space defined by saidcenter section; d. a second air inlet conduit merging tangentially withthe inner space defined by said bottom section, in the zone of saiddischarge end; said second air inlet conduit being oriented towards saiddamper means in a direction opposite to the orientation of said firstair inlet conduit; e. means disposed externally of said furnace fordividing the space surrounding said furnace into an upper external spacesurrounding said top and center sections and into a lower external spacesurrounding said bottom section; f. a flue gas outlet conduitcommunicating with the inner space defined by center section; g. aremovable solid waste feeding device communicating with said chargingend and being supported by said top section; h. a liquid waste feedingdevice communicating with said charging end and being supported by saidtop section; i. A flue gas filter having an input connected to said fluegas outlet conduit; filter candles; means for replacing the filtercandles; a flue gas surge chamber; means for removing ashes from theflue gas surge chamber; and an outlet; and j. a removable glove boxattached to said discharge end of said furnace; said glove box having aninlet provided with a twopart gate for controlling the outflow of solidmaterial from said furnace and an outlet provided with a coarse grate.2. An apparatus as defined in claim 1, wherein said flue gas filter hasa square shape tapering down towards the bottom to an aperture for theremoval of ashes.
 3. An apparatus as defined in claim 1, wherein saidliquid waste feeding device includes a double tube formed of an innertube for feeding the burnable liquid into the furnace and an outer tubefor admitting compressed air to dissipate the liquid and cool the innertube.
 4. An apparatus as defined in claim 1, the inner space defined bysaid center section having a cylindrical configuration, the inner spacedefined by said bottom section having an upper chamber portion ofdownwardly tapering conical shape, the diameter of a lower terminus ofsaid upper chamber portion being one third the diameter of an upperterminus of said upper chamber portion; the inner space defined by saidbottom section further having a lower chamber portion of uniformcylindrical shape, said lower chamber portion adjoining said upperchamber portion and extending downwardly therefrom.
 5. An apparatus asdefined in claim 1, said solid waste feeding device including a vesselhaving a floor; means defining an opening in said vessel floor forcommunicating with said charging end of said furnace; a slide dampermovably supported in said vessel and cooperating with said opening tocontrol the discharge of solid wastes from said vessel into saidfurnace; and means defining a further opening in said vessel forintroducing solid wastes thereinto.
 6. An apparatus as defined in claim5, said slide damper including a feeder plate movable along the vesselfloor, means defining an aperture in said plate, said aperture havingsubstantially the same dimensions as said opening in said vessel floor;an upright, laterally closed, open-ended, upwardly slightly tapered hooddisposed above said aperture and affixed to said feeder plate; anactuating rod affixed at least indirectly to said feeder plate andprojecting outwardly from said vessel; and power cylinder meansoperatively connected to said actuating rod.
 7. An apparatus as definedin claim 6, further including a shielding plate affixed to said vesseland extending parallelspaced from said vessel floor adjacent saidopening; said shielding plate extending between said hood and saidfeeder plate above said aperture in said feeder plate when said feederplate covers said opening in said vessel floor.
 8. An apparatus asdefined in claim 7, wherein said feeder plate is made of ceramic andsaid shielding plate is made of metal.
 9. An apparatus as defined inclaim 1, said glove box further having two oppositely arrangedobservation windows; said two-part gate being pivotally supported andcovering said observation windows when in a position in which it freesthe inlet of said glove box.
 10. An apparatus as defined in claim 1,said filter candles having upper ends connected to said means forreplacing the filter candles; said filter candles having lower endsdetachably connected with said means for removing ashes from the fluegas surge chamber.
 11. An apparatus as defined in claim 1, wherein saidgas filter includes means defining a cylindrical chamber below saidfilter candles, said cylindrical chamber constituting said flue gassurge chamber.
 12. An apparatus as defined in claim 1, wherein said gasfilter includes means defining a square chamber below said filtercandles, said square chamber constituting said flue gas surge chamber.13. An apparatus as defined in claim 1, wherein saId means for removingashes from the flue gas surge chamber is constituted by a glove boxattached to the outlet of said gas filter.
 14. An apparatus as definedin claim 13, said glove box attached to the outlet of said gas filterhaving several glove ports, at least one tool lock, at least one window,a movable damper closing and clearing the outlet of said gas filter forthe removal of ashes from the flue gas filter and a coarse gratedisposed at the lower end of said glove box attached to the outlet ofsaid gas filter.
 15. An apparatus as defined in claim 1, said means forreplacing the filter candles in the flue gas filter including a. afilter candle support plate from which said filter candles aresuspended; b. a removable box attached to an upper part of the gasfilter; c. lifting means supported by said box for vertically movingsaid filter candle support plate; d. at least one tool lock provided insaid box; and e. an arresting device affixed to said box for lockingsaid filter candle support plate in a lifted position within said box.16. An apparatus as define in claim 1, wherein said gas filter includesa frame and a vertically movable lid; said means for replacing thefilter candles includes a fixed glove box disposed about said lid andpermanently affixed to said frame.
 17. An apparatus as defined in claim16, wherein said fixed box has a sufficient inner width to allow the lidto be moved up and down therein, several glove ports, at least one toollock, at least one window and a push rod connected with the lid andpenetrating the wall of the fixed box in a gastight manner, an arrestingdevice for locking the lid when pulled up beyond the level of the windowfor the replacement of filter candles.
 18. An apparatus as defined inclaim 1, said center section including a multilayer refractory ceramiclining; further comprising angular brackets supported on said bottomsection; at least the outer layers of said lining being supportedupright by said angular brackets.